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Compression test, 12cR2

HCC is available only on Oracle supplied storage, such as a ZFS storage appliance or (as in this case) an Exadata engineered system. Furthermore, it occurs only for direct loads: in my examples, using CTAS. This is the script I'm running for this (not very scientific) test:

The results show that the deduplication comes in at three or four to one compression ratio, and that HCC is around ten to one for Query Low, twenty to one for the others. The astonishing figure is that the Archive High algorithm is nearly eight times as slow as no compression. Most of the other algorithms are actually faster than no compression.
The lesson from this? Compression may give you huge space savings, but test the algorithms carefully. In another article I'll look at the effects on subsequent SELECTs and DMLs.
Tests done on database release 12.2.0.0.3, Exadata.
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John Watson
Oracle Certified Master DBAhttp://skillbuilders.com